Microbes (e.g., algae, bacteria, fungus, mildew and mold) typically grow on warm wet surfaces. The presence and growth of such microbes is usually undesirable. For example, in the roofing industry, the discoloration of roofing materials (e.g., asphalt, wood or plastic shingles; ceramic or metal tile; slate; bituminous roofing membranes; metal sheeting; roll roofing; etc) is largely attributable to the growth of various types of blue-green algae, most commonly Gloeocapsa, and Scytonema, as well as various types of green algae in certain environments. Current approaches to solve this problem include such things as regular roof cleanings and installation of zinc metal strips on the roof. Another approach, particularly applicable to conventional asphalt shingles, is the incorporation of copper releasing granules along with standard color granules applied to the surface of the asphalt mat during the shingle manufacturing process. There are several disadvantages associated with each of these approaches. Roof cleanings, especially in southern regions of the US, can, be necessary on at least an annual basis to maintain a clean roof, since this approach provides no means of preventing the return of the microorganisms. Furthermore, the cleaning process may actually damage or shorten the life of the roof. Zinc strips may provide an algae free roof, but are often aesthetically objectionable, since they are clearly visible on the roof. Shingles with the copper containing granules can be effective for long terms without detracting from the desired visual effect, but this approach fails to address the need to protect existing roofs which were not originally covered with such shingles. Additionally, while well suited for use by the manufacturer of asphalt shingles, copper containing granules are much less applicable for other types of roofing materials (e.g., wood shingles, ceramic tile, slate, etc.). In addition, the prior art has failed to address the need for an anti-microbial delivery system which is practical and compatible with other building related structures (e.g., air conditioning and heating ducts, walls, ceilings, exterior siding, decks, patios, etc.) or other structures (e.g., fences, the inside of refrigeration units, cooling towers, animal cages, ductwork etc.).
Thus, there exists a need for an effective and versatile delivery system for an anti-microbial agent which can be used on existing roofs, as well as in the manufacture of new roofing materials, and on other structures.